Dental tool

ABSTRACT

A dental tool is described for use in the impression process of dental prosthesis. The hand-held dental tool includes an impression material cartridge releasably connected to a cylindrical tool housing. A controlled amount of air pressure is directed from a source through a hose and into a bore of the cylindrical housing to force a freely movable piston against the rear end of an elongated plunger which has its forward end slidably mounted in the cartridge. The plunger, in turn, forces a flowable impression material along the interior of the cartridge to flow from a reduced opening.

nited States Patent Condon [451 Aug. 6, 1974 DENTAL TOOL 22 Filed: May 22,1972

[2]] Appl. No.: 255,861

Related US. Application Data [63] Continuation-impart of Ser. No. H5595, April 30,

I971, abandoned.

3,641,673 2/1972 Jochems 32/60 Primary Examiner-Robert Peshoek Attorney, Agent, or Firm Wells, St. John & Roberts [57] ABSTRACT A dental tool is described for use in the impression process of dental prosthesis. The hand-held dental tool includes an impression material cartridge releasably connected to a cylindrical tool housing. A controlled amount of air pressure is directed from a source through a hose and into a bore of the cylindrical housing to force a freely movable piston against the rear end of an elongated plunger which has its forward end slidably mounted in the cartridge. The plunger, in turn, forces a flowable impression material along the interior of the cartridge to flow from a reduced opening.

7 Claims, 14 Drawing Figures PATENTEB M19 61974 SHEEI1 0F FIGI/EE 3 FMWM 4 FIGURE 2 PATENTEmuc 61974 SHEET 2 OF 3 FIGI/WE 5 DENTAL TOOL RELATED APPLICATIONS This application is a continuation-in-part of the application Ser. No. 135,595 filed April 30, 1971, now abandoned, having the same title.

BACKGROUND OF THE INVENTION This invention relates to dental tools and more particularly to those tools used in taking impressions for dental prosthesis.

Most impressions for dental prosthesis are presently made by manually applying a quick-drying, flowable impression material about the area of a patients mouth to be reshaped. The material is usually applied through use of a hand-operated impression material syringe.

The impression material, consisting mainly of a flowable rubber base and drying agent, is quite viscous requiring a force of approximately 40 psi to initiate and maintain flow from the present impression material syringes. It is difficult for the operator to manually apply a force to the syringe sufficient to create a pressure in excess of 40 psi and at the same time guide the syringe to deposit the material accurately in a patients mouth. At such force levels it is easy for the operator to loose his grip and jab the end of the syringe against the mouth and facial tissues of the patient. Furthermore, the operation is quite fatiguing causing the arm and hand muscles to tighten up affecting the operators dexterity.

With one hand operating the impression material syringe, the other must gently hold the patients lip or cheek away from the critical area. An assistant is also required to operate a suction tube to remove tooth chips and to keep the tooth and gum area dry while the impression material is being applied. The result is that the patient often has at least one finger, the syringe and a suction tube in his mouth at one time, causing discomfort.

One of the principal objects of this invention is to provide a powered dental tool for applying the impression material accurately and with complete safety into the patients mouth.

An additional object of this invention is to provide a dental tool for accurately injecting the impression material in readily controllable quantities.

A further object of this invention is to provide a dental tool that is powered by a source readily available in dentists offices which will not require the modifications of existing equipment.

A further object of this invention is to provide a dental tool that can be adapted to accommodate prior dental devices used in the impression process of dental prosthesis.

A further object of my invention is to provide a dental tool having the capability of keeping the impression area dry and free from tooth particles while the impression material is being ejected therefrom.

A further object of my invention is to provide such a dental tool that is relatively inexpensive to manufacture and easy to operate.

An additional objectof this invention is to provide a dental tool for applying impression material into the with the impression material with a mechanism for locking the cartridge to the tool.

These and other objects and advantages of this invention will become apparent upon the reading of the following detailed description of a preferred and alternate embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred and alternate embodiment of this invention is illustrated in the accompanying drawings, in which:

FIG. 1 is an isometric view of a typical prior art disposable impression material cartridge;

FIG. 2 is an orthographic side view showing a dental tool incorporating the principal features of this invention;

FIG. 3 is an orthographic cross-sectional view taken along line 33 in FIG. 1 in the direction of the arrows located thereon;

FIG. 4 is an orthographic end view of my invention taken along line 4-4 in FIG. 1 in the direction of the arrows located thereon;

FIG. 5 is a pictorial view illustrating the dental tool being held by an operators hand during the application of impression material to a tooth area;

FIG. 6is an isometric view of a typical prior art reusable impression material syringe.

FIG. 7 is an exploded isometric fragmentary view of an alternate embodiment of my invention, its parts and their relation to one another;

FIG. 8 is an orthographic frontal view taken along line 8-8 in FIG. 7 in the direction of the arrows located thereon;

FIG. 9 is an isometric view of a disposable impression material cartridge;

FIG. 10 is a fragmentary isometric view of a modified disposable impression material cartridge;

FIG. 11 is an isometric view of an alternate embodiment of the dental tool including illustrating a locking means for securing the cartridge to the tool;

FIG. 12 is a rear end view of the dental tool illustrated in FIG. 11;

FIG. 13 is an orthographic side view of the dental tool illustrated in FIG. 11 illustrating the alternate positions: of the locking means with the locking means shown in solid line in a locking position and in dotted line in an unlocking position; and

FIG. 14 is an orthographic longitudinal vertical crosssectional view of the dental tool illustrated in FIG. 11.

DETAILED DESCRIPTION OF A PREFERRED AND ALTERNATE EMBODIMENT A presently available impression material syringe 10 is shown in detail in FIG. 1. Syringes of this type are generally purchased in multiples and are inexpensively constructed to facilitate their disposal after use. The syringe 10 comprises an elongated tube 11 having a reduced end 12 and an open end 15. Reduced end 12 rigidly supports a curved discharge tube 13 which tapers to a reduced opening 14. The open end 15 of the tube 11 rigidly supports a finger grip 16 which is formed by opposed radially extending ears l7 and 18.

The open end 15 and the interior of tube 11 slidably accommodate an elongated plunger 20. The plunger 20 comprises an elongated body 21 having a forward end 22 and a rear end 24. The forward end 22 of plunger structurally mounts a rubber piston 23. The rubber piston 23 is of a diameter slightly larger than that of the interior of tube 11 to provide an airtight but frictionally slidable relationship between the piston and the interior of tube 11. The rear end 24 of plunger 20 has a discshaped plunger cap 25.

Before operating the syringe 10, the plunger 20 must be removed from the tube 11 to allow the operator or his assistant to partially fill the tube 11 with impression material 19. The plunger 20 is then pushed back into the tube 11. To operate the syringe 10, the operator must grasp the syringe in one hand by simultaneously engaging the projecting ears l7 and 18 with the index and middle fingers while the thumb engages the plunger cap 25. The operator then attempts to reduce the distance between his thumb and fingers thereby forcing the plunger 20 further into the tube 11. If enough force has been applied, the plunger will move the piston 23 and thus, the impression material toward the discharge tube. The impression material being flowable, is thereby forced to exit through the reduced opening 14 of the syringe to a patients tooth or gum. As previously mentioned, the impression material 19 is quite viscous, requiring a very strong grip to dispense the material from the syringe 10.

The syringe 10 as described above may be utilized as a replaceable or refillable cartridge 10 of a dental tool 26 illustrated in FIG. 2. As a component of the dental tool 26, the finger grip 16 becomes a male connecting element 16 releasably connectable to a corresponding female connecting element 31.

As seen in FIG. 2, the dental tool 26 further includes a hollow elongated cylindrical tool housing 27 with female connecting elements 31 at an open end 30 and a male threaded air supply fitting 37 at a partially closed end 36. The tool housing has a cylindrical cross that is sufficiently small to enable the tool to be conveniently held in one hand between the thumb and the index finger in a manner similar to holding a pencil.

The tool housing 27 has an interior bore 28 of a diameter slightly larger than that of the plunger cap of the impression material cartridge 10. The bore 28 slidably supports a piston 29 which is freely slidable along the bore while maintaining an airtight contact with the inner surface of the bore 28.

The female connecting element 31 located on the periphery of open end 30, is formed by radially opposed shoulders 32 and 33. Shoulders 32 and 33 extend radially outward beyond open end then inward forming opposed radial slots 34 and 35. Slots 34 and 35 are spaced apart to form a recess at the open end 30 of the cylinder 27. Recess 40 enables the ears 17 and 18 of the male connecting element 16 to be inserted therein and then rotated to move the ears l7 and 18 into the slots 34 and 35 respectively of the female engaging elements 31.

The partially closed end 36 rigidly supports a threaded male air supply fitting 37 which contains a main air supply tube 38 and an auxillary air supply tube 39. The fitting 37 conforms in configuration to accommodate a female air supply fitting 41 (FIG. 5) which are common to the dental arts and available in most dentist offices. The main air supply tube 38 extends longitudinally through fitting 37 to supply air under pressure of between 5 psig and 60 psig from a source (not shown in drawings) available in about all dental facilities. The auxillary tube 39 extends partially through fitting 37 and then outwardly to extend along the outside of air cylinder 27 and the attached cartridge 10 to the reduced opening 14. The auxillary tube 39 is held against air cylinder by an annular clip 42 and removably attached to cartridge 10 by a spring clip 43 and a slidable clip 44.

To operate the dental tool 26, a filled impression material cartridge 10 is fitted to the air cylinder 27 by inserting end 24 of the plunger 20 including cap 25 through the open end 30 and into the bore 28 of the air cylinder 27. The plunger cap 20 comes in contact with the piston 29 and moves it back to a position near end 36 of cylinder 27. The cartridge is angularly oriented to enable the end 15 to move into recess 40 of the cylinder 27. The operator then rotates the cartridge 10 relative to the air cylinder 27 to move the ears 17 and 18 into the slots 34 and 35 respectively to interlock the male connecting element 16 within the female connecting element 31. Spring clip 43 is then attached near the reduced end 12 of the cartridge 10 and the slidable clip 44 is moved onto the reduced opening 14.

The operator holds the tool in one hand by engaging the tool between the thumb and the index finger in a manner similar to holding a pencil (FIG. 5). The tool 26 may then be operated by regulating the air pressure through hose simultaneously to auxillary tube 39 and to the bore 29 of air cylinder 27. The air pressure forces the free piston 29 against the plunger cap 25 to move the plunger 20 towards the discharge tube 13 thus forcing the impression material 19 to exit from the reduced opening 14 of the cartridge 10. Flow of the impression material 19 from the tool 27 is controlled by the operator through a foot-controlled valve or other air pressure control means common to the dental art.

By utilizing dental tool 26, the operator can deposit the impression material 19 in a patients mouth while keeping the impression area dry to allow the impression material to adhere. Since the operator is not required to manually force the impression material from the cartridge, the material can be effortlessly deposited with greater care and accuracy. The operator is required to use only one hand to hold the tool 26, enabling the other hand to operate a suction tube or hold the patients cheek or lip away from the impression area.

After the impression has been made, the disposable cartridge 10 may then be removed from the housing 27 and thrown away. The spend cartridge 10 is removed from the housing 27 by disengaging clips 43 and 44 then rotating the tube 11, relative to housing 27, to disengage the male connecting means 16 of the cartridge 10 from female connecting means 31 of the air cylinder. The plunger 20 is then retracted from the bore 28 by axially pulling the cartridge 10 away from the housing 27.

FIG. 6 illustrates a presently available re-usable impression material syringe 46. The re-usable syringe 46 consists of a tube 47. The tube 47 has external threads at a discharge end 48 and at an open end 52. The discharge end 48 threadably accepts a retaining cap 51 which holds a curved discharge tube 49 thereto. Discharge tube 49 may be removed for cleaning purposes or for replacement. The open end 52 threadably supports a finger grip 53 which is also removable for cleaning purposes.

An elongated plunger shaft 54 supports a piston 55 at a forward end and threadably supports a disc-shaped plunger cap 57 of a diameter somewhat larger than that of the plunger cap of cartridge 10.

The operation of the re-usable syringe 46 is similar to the operation of the disposable syringe 10 as described above. However, the construction of the re-usable syringe 46 is such that it may be dismantled for cleaning purposes, then re-assembled for repeated use.

The re-usable syringe 46 may be utilized as a reusable, replaceable impression material cartridge 46 of an alternate embodiment of dental tool 26 as shown in FIG. 7. However, finger grip 53 is replaced with a male connecting adaptor 58 and the plunger cap 57 is replaced by a plunger. cap 63 of a smaller diameter.

The male connecting adaptor 58 is comprised of opposed projecting ears 59 and 60 of dimensions similar to ears 17 and 18 of cartridge 10. An internally threaded cap 61 is rigidly attached to ears 59 and 60 to provide means for attaching adapter 59 to the threaded end 52 of hollow cylinder 47. Plunger cap 63 is of a diameter sufficient to allow its passage into the bore 28 of air cylinder 27.

The re-usable cartridge 46 is attached to the housing 27 using the same procedure as described above for attaching the disposable cartridge 10.

The operation of the alternate embodiment of my invention is similar to that of the preferred embodiment. As previously described however, upon completion of the impression making process, the re.-usable cartridge 46 may be dismantled for cleaning purposes then reused at a later time.

An alternate embodiment of the dental tool 26 is illustrated in FIGS. 9-14. FIG. 9 shows a syringe having an elongated tube body 71 with a reduced end 72 and an open end 74. An annular shoulder 75 is formed at the reduced end 72. Diametrically opposed projecting ears 77 and 78 are formed at the opened end 74. The syringe 70 includes a plunger 80 having an elongated body 81 with a forward piston end 82 and a rear end 83. A plunger cap 84 formed at the rear end 83.

The dental tool 26 includes a cylindrical housing 88 having an interior bore 90 forming an open end 91 and a closed end 92. A free piston is slidably mounted in the interior bore for moving between the ends. A stop pin 94 is positioned adjacent the open end 91 to prevent the free piston 93 from being ejected from the open end 91.

A main air passage 96 is formed in the closed end 92 communicating with the interior bore 90 to apply pressurized air to the free piston to drive the free piston from the closed end 92 toward the open end 91.

An auxiliary passageway 97 is formed in the cylindrical housing 88 and extends from the closed end 92 through the body of the housing to a location adjacent the open end 91 terminating in a open fitting 98.

An important feature of this embodiment is a locking means 100 for releasably securing the syringe 70 to the cylindrical housing to prevent the inadvertent ejection of the syringe while air pressure is being applied against the free piston 93. The locking means includes a lever 101 that has a front end 102 that extends to the reduced end 72 of the syringe as'illustrated in FIGS. 10, 12 and 13. The lever has a rear end 103 that extends to the closed end 92 of the cylindrical housing. The locking lever 101 has an intermediate angular section 105 that circumscribes the open end 91 of the housing. The lever 101 is pivotally mounted to the cylindrical housing by pivot pins 106 that connect with the angular section 105 to enable the lever 101 to be pivoted intermediate its ends. The lever 101 includes a forward section 107 that extends forward of the angular section 105 to the front end 102. The forward section 107 has a length substantially equal to the length of the elongated tube 71. The front end 102 has a nose section 108 with forked elements 111 that extend angularly about the angular shoulder 75 for engaging the shoulder to prevent the ejection of the syringe 70 when the locking means is in a locking position. A fine air line 112 extends from the nose section 108 in a curved manner along the reduced end 72 to direct air into the patients mouth adjacent the outlet of the syringe to maintain the tooth area receiving the impression material dry and to force the impression material against the tooth and down between the gum and the tooth to provide a more accurate impression. The lever 101 has a handle section 114 that extends rearward from the angular section 105 to the rear end 103. The handle section 114 has a length substantially equal to the length of the cylindrical housing 88. A heel portion 115 is formed at the rear end 103 for engaging the exterior of the closed end 92. A flexible line 117 extends from the fitting 98 to the curved fine air line 112 to direct the air from the auxiliary passageway 97 to the line air line 112.

An additional feature of this embodiment is a safety valve means 120 for preventing the buildup of pressure behind the free piston 93 until the locking means 100 is closed and for venting the pressure behind the free piston 95 when the locking means 100 is released. The safety valve means 120 includes a bent hole 121 formed in the housing 88 near the closed end 92. A rubber plug 122 is mounted on the locking lever 101 in alignment with the vent hole 121 to fill and close the vent hole 121 when the locking lever 101 is closed and open the hole 121 when the lever is open.

During the operation of the embodiment illustrated in FIGS. 9-14, the syringe 70 is filled with impression material and then the syringe is loaded into the cylindrical housing with the plunger 80 extending through the open end 91 into the interior bore 90. The syringe is rotated to interconnect the ears 77 and 78 with corresponding interlocking means of the cylindrical housing. During the loading procedure, the locking lever 101 is in the unlocking position illustrated in dotted lines in FIG. 13. After the syringe 70 has been loaded into the cylindrical housing 88 the locking lever 101 la pivoted to the locking position with the forward position 107 extending over the elongated tube 81 with the nose section 108 engaging the angular shoulder 75 as illustrated in FIGS. 11 and 14. The handle section 114 is pivoted to engage the exterior of the cylindrical housing 88 with the heel 115 engaging the rear end and the plug 122 closing the vent hole 121. In this manner should the ears 77 and 78 be in improper alignmentor should breakage occur, the syringe cannot be removed from the cylindrical housing.

The dental tool is held by the operator between his thumb and index finger. The operator projects the reduced end of the syringe and the fine air line 112 into the patients mouth. The air through the fine air line 112 is used to force the impression material against the tooth and between the tooth and gum and to maintain the tooth area dry to provide good cohesion between the impression material and the tooth area. The operator can adjust the amountof air pressure applied to the free piston 93 through a foot valve or other means normally found in dental offices. With air applied to the free piston the free piston is moved forward to engage the plunger cap 84 and to drive the plunger 80 to eject the impression material. When the free piston reaches the open end 91, it engages the stop pin 94 to prevent the free piston from providing additional force to the syringe. Stop pin 94 also prevents the free piston from being blown from the cylindrical housing 88 when the syringe is removed. The stop pin 94 provides a safety feature to prevent the free piston from becoming a dangerous flying object. At the conclusion of the operation, the operator opens the lever 101 to release the air pressure behind the free piston 93 and to release the cartridge for removal.

The syringe 70 as shown in FIG. 10 may have a reduced end 82 that is removable from the elongated tube body 71. In this manner, different size reduced ends 72 may be applied to the syringe as desired.

Modifications can obviously be made in the specific features shown and therefore the foregoing description is not intended to limit or restrict the scope of the application, the invention being set out in the following claims.

Having thus described my invention, I claim:

1. A dental tool for applying impression material onto a patients tooth; comprising a cylindrical cartridge having an open end and a reduced end with a reduced opening, in which the cartridge is filled with a flowable impression material;

an elongated plunger having a forward end slidably mounted in the cartridge for pushing the impression material out the reduced opening and a rear end extending outward from the open end;

a cylindrical housing having a bore with an open end for receiving the rear end of the plunger therein; said housing having a free piston slidably mounted in the bore for engaging the rear end of the plunger;

an air line communicating with the bore behind the piston and connectable to a source of air pressure to force the free piston toward the open end to push the plunger and thereby dispense the impression material from the reduced end of the cartridge;

a releasable connection means for operativcly connecting the open end of the cartridge to the cylindrical housing; and

a locking lever pivotally mounted to the cylindrical housing in which the lever has a projecting section extending forward of the housing terminating in a nose element for releasably gripping the reduced end of the cartridge when the cartridge is operatively connected to the cylindrical housing.

2. The dental tool as defined in claim 1 wherein the free piston has a diameter greater than the crosssection of the rear end of the plunger.

3. The dental tool as defined in claim 1 wherein the open end of the cartridge has a male connector element associated therewith and wherein the open end of the housing has a female connector element therewith for receiving a male connector element and for releasably interlocking with the male connector element to operatively connect the cartridge to the housing.

4. The dental tool as defined in claim 3 wherein the male connector element includes shoulder projections extending radially outward from the open end of cartridge and wherein the female connector element includes a recess for receiving the open end of the cartridge therein with corresponding shoulders for engaging the male connector shoulders when the open end of the cartridge is inserted into the pocket and rotated relative to the housing.

5. The dental tool as defined in claim 1 wherein the locking means includes a handle section for extending alongside the exterior of the housing.

6. The dental tool as defined in claim 1 wherein the housing has an air passageway communicating with the air line and extending to the reduced end of the cartridge for directing air into the patients mouth to keep the tooth receiving the impression material dry.

7. The dental tool as defined in claim 1 further comprising a safety valve means for preventing the inadvertent application of air pressure to the free piston. 

1. A dental tool for applying impression material onto a patient''s tooth; comprising a cylindrical cartridge having an open end and a reduced end with a reduced opening, in which the cartridge is filled with a flowable impression material; an elongated plunger having a forward end slidably mounted in the cartridge for pushing the impression material out the reduced opening and a rear end extending outward from the open end; a cylindrical housing having a bore with an open end for receiving the rear end of the plunger therein; said housing having a free piston slidably mounted in the bore for engaging the rear end of the plunger; an air line communicating with the bore behind the piston and connectable to a source of air pressure to force the free piston toward the open end to push the plunger and thereby dispense the impression material from the reduced end of the cartridge; a releasable connection means for operatively connecting the open end of the cartridge to the cylindrical housing; and a locking lever pivotally mounted to the cylindrical housing in which the lever has a projecting section extending forward of the housing terminating in a nose element for releasably gripping the reduced end of the cartridge when the cartridge is operatively connected to the cylindrical housing.
 2. The dental tool as defined in claim 1 wherein the free piston has a diameter greater than the cross-section of the rear end of the plunger.
 3. The dental tool as defined in claim 1 wherein the open end of the cartridge has a male connector element associated therewith and wherein the open end of the housing has a female connector element therewith for receiving a male connector element and for releasably interlocking with the male connector element to operatively connect the cartridge to the housing.
 4. The dental tool as defined in claim 3 wherein the male connector element includes shoulder projections extending radially outward from the open end of cartridge and wherein the female connector element includes a recess for receiving the open end of the cartridge therein with corresponding shoulders for engaging the male connector shoulders when the open end of the cartridge is inserted into the pocket and rotated relative to the housing.
 5. The dental tool as defined in claim 1 wherein the locking means includes a handle section for extending alongside the exterior of the housing.
 6. The dental tool as defined in claim 1 wherein the housing has an air passageway communicating with the air line and extending to the reduced end of the cartridge for directing air into the patient''s mouth to keep the tooth receiving the impression material dry.
 7. The dental tool as defined in claim 1 further comprising a safety valve means for preventing the inadvertent application of air pressure to the free piston. 